The present invention relates generally to heater fabricating techniques and more particularly to processes for joining heating elements and their associated mounting hardware, and particularly to such a process for fabricating an electric heater assembly for encircling a hermetic compressor housing.
The refrigeration and air conditioning industry generally has long recognized the utility of providing a heating element to raise the temperature of the compressor lubricant above that of the refrigeration system refrigerant to minimize the mixing of those two materials and the distribution of the lubricant throughout the system.
The current technique for providing such a heater is to join the opposite ends of a tensioning band to the opposite ends of the heater element and then tighten the band so that the assembly firmly grips the outside of the housing. The tensioning band is frequently constructed like a typical automobile radiator hose clamp, that is, it is formed from a pair of metallic strips, one of which supports a threaded member, while the other includes a series of equally spaced transverse slots which engage a portion of the threads of that threaded member so that when the threaded member is turned, one strip is moved relative to the other.
While this known system has met with considerable commercial success, the attachment of the tensioning member ends to the heater element ends continues to be a source of substantial expense, as well as a source of heater failure, due to galvanic action, where dissimilar metals are in contact.
More particularly, the joining of each tensioning member end to its respective heater element end is accomplished currently by providing a metal component formed to be clamped about the heater element near its end and welded to the corresponding end of the tensioning member. Thus, at each heating element end, there are two interfaces between dissimilar metals, a forming operation, a welding operation, and a clamping operation required to join the tensioning member end to the heating element end. Industry use of at least three different materials for the outer layer of the sheathed heating element further compound the problem of appropriate material selection to minimize electrolytic action at these metal to metal junctions.